JPH1038212A - Waste heat boiler structure attached to waste thermal decomposing furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate a steam temperature at a superheater outlet to a proper temperature lower than a maximum working temperature by a method wherein dampers are respectively arranged at the outlet of a bypass passage and an exhaust gas passage in which superheaters are disposed, and a flow rate of exhaust gas is regulated. SOLUTION: A partition wall 2-3 is arranged in the same direction as the inflow direction of combustion exhaust gas in parallel to superheaters in a combustion exhaust gas passage in which superheaters 3-1 and 3-2 are disposed. A bypass passage T3-1 is formed between the partition wall and a partition wall 2-2. Dampers 8-1 and 8-2 being respectively openable are then arranged at the outlet of the bypass passage T3-1 and the outlet of a combustion exhaust gas passage T3-2 in which the supporters 3-1 and 302 are disposed. Through the openings of the dampers 8-1 and 8-2, an amount of exhaust gas to each heat-exchanger is regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to secondary combustion in which waste requiring treatment such as general waste and industrial waste is treated in a waste treatment furnace such as a waste melting furnace, and the generated pyrolysis gas is burned. The present invention relates to a steam temperature control system for a superheater in a waste heat boiler installed downstream of a furnace.

[0002]

2. Description of the Related Art Conventionally, pyrolysis gas containing combustible dust generated in a waste pyrolysis furnace is burned in a secondary combustion furnace, and high-temperature flue gas is cooled while being inverted by a waste heat boiler provided with a superheater. Have been.

[0003] Explaining the conventional example with reference to FIG. 2, the flue gas is about 850 ° C at the inlet of the waste heat boiler 1, which is lower and upper parts of the partition walls 2-1 and 2-2 of the waste heat boiler 1. The gas is cooled to about 650 ° C. while the gas flow is reversed twice, and the exhaust gas flows into the superheaters 3-1 and 3-2 from above and is cooled to about 500 ° C., and further twice in the evaporator tube group 4 It is cooled to about 300 ° C. while being inverted, and guided to the downstream equipment.

On the other hand, boiler generated steam (about 230 ° C.)
Is guided from the air / water drum 5 to the primary superheater 3-1 and is once heated to about 280 ° C., and then reduced to about 250 ° C. by the water spray type desuperheater 6, and It is led to 3-2 and superheated to a preset outlet steam temperature of 300 ° C.
Here, since the amount of combustion exhaust gas and the gas temperature to the superheaters 3-1 and 3-2 vary depending on the quality of waste treated in the waste pyrolysis furnace, the amount of heat absorbed by the superheater also varies, and the superheat reduction device 6 The water injection amount is automatically adjusted at any time so as to reach the set outlet steam temperature.

[0005]

The conventional method has the following problems.

[0006] First, the combustible dust contained in the pyrolysis gas generated in the waste pyrolysis furnace is not constant, changes due to fluctuations in the quality of the refuse, etc., and more than expected combustible dust is generated in the secondary combustion furnace. In some cases, it may scatter. In such a case, the amount of combustion in the secondary combustion furnace also becomes excessive, the amount of combustion exhaust gas or the temperature of exhaust gas increases, and the amount of heat exchange in the superheater increases due to an increase in the heat input source to the boiler superheater. As a result, the primary and secondary superheater outlet steam temperatures exceed the maximum operating temperature, which is problematic.

Secondly, even at the time of starting up the furnace where the amount of steam generated in the boiler is small, the steam temperature at the outlet of the primary superheater changes to a higher value. Absent.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for burning a pyrolysis gas containing combustible dust generated in a waste pyrolysis furnace.
In a waste heat boiler provided downstream of the next combustion furnace, forming a plurality of combustion exhaust gas passages through a partition wall in the main body thereof, and arranging a superheater in one of the passages, In the arranged flue gas passage, a partition wall is arranged in the same direction as the inflow direction of the flue gas and parallel to the superheater to form a bypass passage, and the outlet of the bypass passage and the superheater are arranged. A damper is provided at each outlet of the exhaust gas passage to adjust the flow rate of each exhaust gas.

In such a configuration, a waste heat boiler structure in which a vertical evaporator is provided in the bypass passage may be used.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a superheater 3-
In the flue gas passage T3 in which 1, 3-2 are disposed, a partition wall 2-3 is disposed in parallel with the superheaters 3-1 and 3-2 to form a bypass passage, and Dampers 8-1 and 8-2 are provided at each exhaust gas outlet to control the flow rate of exhaust gas, so that combustible dust contained in the pyrolysis gas generated in the waste pyrolysis furnace is more secondary than expected. When the fuel is scattered into the combustion furnace, the amount of combustion becomes excessive, the amount of combustion exhaust gas or the temperature of exhaust gas rises, and the steam temperature at the superheater outlet shifts to a higher value, the opening of these dampers 8-1, 8-2 is increased. Automatically operates from the normal opening to the superheating side closing direction and the vertical evaporator tube side opening direction to control the heat input source (exhaust gas amount) to the superheater side so that it can be adjusted to the normal steam temperature. I am doing it.

Further, a vertical evaporator tube 7 is provided in the bypass passage to compensate for the insufficient cooling capacity of the evaporator tube group 4 due to an increase in the heat input source, and to provide heat to the economizer installed downstream of the boiler. We try to reduce the load.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

In the drawing, reference numeral 1 denotes a waste heat boiler, in which a plurality of combustion exhaust gas passages T1, T2, T3, T4 are provided via partition walls 2-1, 2-2, 2-4, 2-5. , T5 are formed, and superheaters 3-1 and 3-2 are disposed in the third exhaust gas passage T3-2.

In the present invention, these superheaters 3-
In the flue gas passage T3 in which 1, 3-2 are disposed,
A partition wall 2-3 is provided parallel to these superheaters in the same direction as the inflow direction of the combustion exhaust gas, and a bypass passage T3-1 is formed between the partition wall and the partition wall 2-2.

Next, a damper 8 which can be opened and closed is provided at the outlet of the bypass passage T3-1 and at the outlet of the flue gas passage T3-2 in which the superheaters 3- and 3-2 are disposed.
1, 8-2 are provided, and the amount of exhaust gas to each heat exchanger is adjusted by the degree of opening of these dampers 8-1, 8-2.

The flow of exhaust gas and steam in such a configuration will be described. The flue gas is approximately 850 ° C. at the inlet of the waste heat boiler 1, and this is generated at the lower and upper parts of the partition wall 2 of the waste heat boiler 1. Approximately 6 while the flow is reversed twice
It is cooled to 50 ° C and the exhaust gas is cooled by superheaters 3-1, 3-2.
The gas flows into the gas passage and the bypass passage from above.

Here, the exhaust gas is usually supplied to each damper 8-.
1, 8-2 is set to a normal opening degree, and the superheater side and the bypass side are distributed at a flow rate of 8: 2, and heat exchange is performed for each, and about 50
It is cooled to 0 ° C. and further cooled to about 300 ° C. while being inverted twice in the evaporator tube group 4 and led to the downstream equipment.

On the other hand, boiler generated steam (about 230 ° C.)
As in the conventional case, the primary superheater 3-1
After being superheated to about 280 ° C, the water spray type superheat reducer 6 controls the temperature of the water to be set at a preset steam temperature at the outlet of the boiler. He is heated to 300 ° C.

As mentioned above, when the heat input source is increased, in the prior art, the primary and secondary superheater outlet steam temperatures are 3 ° C.
In the present invention, the opening degree of each damper 8-1 and 8-2 is automatically operated from the normal opening degree to the superheating side closing direction and the bypass side opening direction to increase the exhaust gas amount. For example, by distributing the flow rates of the superheater side and the bypass side at a ratio of 5: 5, the primary and secondary superheater outlet steam temperatures are adjusted to normal temperatures of 280 ° C. and 300 ° C., respectively.

Next, in the invention according to claim 2 of the present application, a vertical evaporator tube 7 is disposed in the bypass passage T3-1. Thus, the lack of cooling capacity of the evaporator tube group 4 due to the increase in the heat input source is compensated for, and the heat load on the economizer installed downstream of the boiler is reduced.

[0021]

As described above, according to the present invention, the following effects are exhibited.

(1) Even if the combustible dust contained in the pyrolysis gas generated in the waste pyrolysis furnace is scattered to the secondary combustion furnace more than expected, the steam temperature at the superheater outlet should be kept at a moderate level below the maximum operating temperature. Temperature can be adjusted.

(2) The temperature of the steam at the outlet of the superheater can be adjusted to a safe temperature even when the furnace is started, for example, when the amount of steam generated in the boiler is small.

(3) In the case of the above (1), the heat load on the economizer installed downstream of the waste heat boiler can be reduced, and the steaming of the economizer outlet water can be prevented.

[Brief description of the drawings]

FIG. 1 shows an example of a waste heat boiler incorporating the device of the present invention.

FIG. 2 shows an example of a conventional waste heat boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste heat boiler 2-1-2-5 Partition wall 3-1: Primary superheater 3-2: Secondary superheater 4: Evaporator tube group 5: Steam drum 6: Superheat reducer 7: Vertical evaporator Pipes 8-1, 8-2: dampers T1 to T5: flue gas passage T3-1: bypass passage T3-2: flue gas passage

Claims (2)

[Claims] 1. A plurality of flue gas passages are provided downstream of a secondary combustion furnace for burning a pyrolysis gas containing combustible dust generated in a waste pyrolysis furnace through a partition wall in a main body thereof. In a waste heat boiler having a superheater disposed in one of the passages, a partition wall is provided in a flue gas passage in which the superheater is disposed, in the same direction as the inflow direction of the flue gas and in parallel with the superheater. To form a bypass passage, and a damper is provided at each of the outlet of the bypass passage and the outlet of the exhaust gas passage where the superheater is provided to adjust the flow rate of each exhaust gas. Waste heat boiler structure attached to waste pyrolysis furnace. 2. A waste heat boiler structure attached to a waste pyrolysis furnace according to claim 1, wherein a vertical evaporator is provided in the bypass passage.